1. Field of the Invention
The present invention relates generally to cable braid splicing devices, and more specifically to a method for splicing together two metal braids used to shield electrical cables from electromagnetic interference (EMI). This invention further relates to a splice that can be installed or repaired by hand, without the use of a special tool, and which will accommodate a wide range of cable sizes.
2. Description of the Prior Art
Electrical cables used for carrying power or electrical signals typically require the use of a metal braid to shield the wires from electromagnetic interference. It is frequently necessary to mechanically and electrically join two shorter pieces of braid on a single cable. In such instances it is desirable to have a braid splice that can be installed and repaired by hand, without the need for tooling. Further, it is desirable to have one component that can accommodate a wide range of cable diameters. Moreover, it is desirable to have a splice that can support axial loading of the cable, allow for cable bending, be resistant to wear from vibration and which will have a low electrical resistance. Finally, it is desirable to have a cable splice that can be installed without having to slide a circular device over the end of the cable.
Splicing methods currently in use fail to meet the foregoing objectives. For example, solderable cable splice systems have good electrical properties but are difficult to install and generally not repairable. Several current splicing methods use a ridged ferrule underlying both braids, along with a type of band to strap around the ferrule. These methods require special tools and require that the ferrule be sized closely to that of the wire cable.
Another method of braid splicing employs a special ferrule and a coiled ribbon spring to hold the braid against the ferrule. The ribbon spring can be installed and removed by hand without tooling, but it requires a specially sized ferrule that must be slid over the cable prior to splicing the ends. The ferrule greatly limits the size range of the splice, and also limits cable flexibility at the splice. In addition the need to slide the ferrule over the cable can make repair difficult for a long cable and may necessitate the removal of end fitting hardware.
Braid splicing methods that employ an inside ferrule have several limitations. Firstly, they cause a sizable raised ridge in the cable that can limit the passage of the cable through holes. Secondly, they are unsuited to cable with tightly woven braids as the braid is incapable of expanding over a ferrule; in that event, other termination methods must be used.
Methods of braid splicing that clamp overlapping braids directly onto the cable can fail by one of two means. If the clamping force is great, the braid will damage the wires under the splice. If the clamping force is too small, the splice will fail under an axial load.
Summarily stated, there are no currently existing cable braid splicing methods that are easily installed by hand and that can be readily repaired or replaced.